Polarity reversing switch for high current loads

ABSTRACT

A fixed base having four contacts arranged in a generally square pattern. A movable switch frame carrying two conductor bars for spanning pairs of the fixed contacts and establishing a current path therebetween. The movable switch frame is movable away from the fixed contacts so that it can be rotated 90* and then moved back into contact with the fixed contacts to form a different circuit configuration between the fixed contacts. A slideable, spring biased mechanism for attaching the conductor bars to the switch frame so as to compensate for minor misalignment between the switch frame and the fixed contacts. The fixed contacts protrude from the base in which they are mounted and have arcuate convex faces to afford uniform contact by the conductor bars. The conductor bars and the base on which the fixed contacts are carried are made of massive conductive material through which are provided passages for a cooling fluid such as water.

United States Patent [191 Paulson Nov. 26, 1974 [75] Inventor: Peter C.Paulson, Pinole, Calif.

[73] Assignee: Electro-Coatings, Inc., Moraga,

Calif.

[22] Filed: July 5, 1973 [2]] Appl. No.: 376,382

[52] US. Cl 200/153 R, 200/1 V, 200/158, 200/165, 200/289, 317/100 [51]Int. Cl HOlh 21/66, HOlh 1/62 [56] References Cited UNITED STATESPATENTS 3,233,059 2/1966 Pridham, Jr. et a1. 200/83 N 3,244,833 4/1966Gillett et al 200/289 X 3,265,846 8/1966 Brechtel et a1. 200/1583,315,057 4/1967 Geltner ZOO/153 R 3,445,609 5/1969 Cardenas 200/1 V3,686,457 8/1972 Dubac et a1. 200/166 BH X 3,778,680 12/1973 Vaneerden200/166 K X FORElGN PATENTS OR APPLlCATlONS l.l50,187 8/1957 France200/166 K 'ver Primary Examiner-James R. Scott Attorney, Agent, orFirmRobert Charles Hill 57 ABSTRACT A fixed base having four contactsarranged in a generally square pattern. A movable switch frame carryingtwo conductor bars for spanning pairs of thefixed contacts andestablishing a current path therebetween. The movable switch frame ismovable away from the fixed contacts so that it can be rotated 90 andthen moved back into contact with the fixed contacts to form a differentcircuit configuration between the fixed contacts. A slideable, springbiased mechanism for attaching the conductor bars to the switch frame soas to compensate for minor misalignment between the switch frame and thefixed contacts. The fixed contacts protrude from the base in which theyare mounted and have arcuate convex faces to afford uniform contact bythe conductor bars. The conductor bars and the base on which the fixedcontacts are carried are made of massive conductive material throughwhich are provided passages for a cooling fluid such as water.

4 Claims, 4 Drawing Figures POLARITY REVERSING swrrcrr FOR HIGH CURRENTLOADS BACKGROUND OF THE INVENTION This invention relates to a highcurrent polarity reversing switch of the type typically employed in thedirect current power supply circuit to electroplating tanks and thelike. More particularly the invention relates to such polarity reversingswitch of increased current carrying capacity.

Polarity reversing switches having certain characteristics common tothose described in more detail hereinbelow are disclosed in US. Pat.Nos. 3,265,846 and 3,315,057. Both of the cited patents disclosepolarity reversing switches that have gained significant commercialacceptance. The present invention discloses certain improvements in suchprior art switches which further enhance their utility.

SUMMARY OF THE INVENTION According to the present invention the currentcarrying capacity of reversing switches of the type disclosed in theabove cited patents is materially increased without substantiallyincreasing the size of such prior art switches. In contrast with acurrent carrying capacity feasible with the prior art switches of about12,000 amperes, the present invention increases the capacity of suchswitches to about 24,000 amperes without materially increasing thephysical size of the switch.

High current switches of the type contemplated by the present inventiontypically employ bus bars of copper having a cross-sectional dimensionof 1 inch X 12 inches. Because the surface area of such bus bars isrelatively small compared to the cross-sectional area of the bus bars anadequate surface area for heat dissipation is not available in certainenvironments. According to the present invention, such bus bars arebored or milled to define a plurality of fluid passages through the busbar and a cooling fluid such as water is supplied to the passages inorder to avoid excessive temperature rises within the bus bars. I

A factor contributing to temperature rise in the bus bars and otherelements of polarity reversing switches is high contact resistance whicharises from low contact pressure. According to the present invention thebus bars that form part of the structure are mounted to afford a slightdegree of movement so that the bus bars can compensate for minormisalignment of the other parts of the structure. The bus bars arespring loaded so that even when slightly misalined they will makeadequate and uniform contact with the stationary parts of the switchwhereby adequate contact pressure and consequent low heat energygeneration is achieved.

Accordingly, it is an object of the present invention to provide acontact reversing switch of high current carrying capability. Thisobject is achieved according to the present invention by providing fluidpassages for cooling fluid within the bus bars and stationary terminalsthat constitute a part of the invention. Accordingly, excessive heat iscarried away by the cooling fluid and high current flow is afforded.

Also contributing to achievement of the above stated object is a mountfor the bus bars that affords a limited degree of movement of the'busbars so that it exerts adequate contact pressure notwithstanding minormisalinements between the parts of the device. The fixed contacts aresomewhat raised above the surface so that contact between the fixedcontact and the bus bars is assured, notwithstanding minormisalinements. Moreover, the bus bar is spring biased toward the fixedcontacts in order to provide good contact pressure.

The foregoing together with other objects, features and advantages ofthe present invention will be more apparent after referring to thefollowing description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a highcapacity polarity reversing switch according to the present invention.

FIG. 2 is a front elevation view of the switch with portions broken awayto reveal certain details.

FIG. 3 is a fragmentary crosssectional view taken along line 3-3 of FIG.2.

FIG. 4 is an enlarged detailed view of the region of FIG. 3 delineatedby line 4-4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly tothe drawing reference numeral 12 indicates a fixed base insulatedstructure on which are mounted four fixed bus bars l4, l6, l8 and 20.The fixed bus bars, in one structure designed according to the presentinvention, are solid copper members having a thickness of 1 inch and awidth of 12 inches. Centrally of base 12 and of the bus bars is a shaft22 on which is supported a movable switch frame designated generally at24. The movable switch frame includes a dish-shaped spring 26, aninsulative support board 28 and two bus bars 30 and 32. The movableswitch frame is moved toward and away from base 12 along shaft 22 and isrotated relative said shaft by means of accouterments as described inUS. Pat. No. 3,315,057, the disclosure of which is incorporated insofaras the same is essential. Suffice it to say when movable switch frame 24is in the position shown in FIG. 1 bus bar 30 bridges fixed bus bars 14and 16 to establish a circuit connection therebetween and bus bar 32bridges fixed bus bars 18 and 20 to establish a circuit there between.When switch frame 24 is rotated in a counterclockwise direction asviewed in FIG. 1, bus bar 30 bridges fixed bus bars 14 and 18 toestablish a circuit therebetween and bus bar 32 bridges fixed bus bars16 and 20 to establish a circuit therebetween. As described in thepatents cited hereinabove, the fixed bus bars 14, l6, l8 and 20 areconnected to the DC power supply and to the electroplating bath in orderthat the polarity of the current supplied to the bath is reversed onrotating movable switch frame 24 as described next above.

The bus bars although they are of solid copper have insufficient coolingsurface relative to their crosssectional area to dissipate heatgenerated during high current operation. In order to maintain thetemperature of the bus bars the present invention provides passagesforrned in the bus bars through which passages a cooling fluid, such aswater, is conveyed. Exemplifying the fixed bus bars is bus bar 14 which,as seen in FIG. 2, includes three parallel vertically extending passages34, 36 and 38. Joining the upper ends of passages 34 and 36 is a milledslot 40 which is closed by an impervious cover 42, braised in placewithin bus bar 14. The opposite end of passage 36 is joined to the lowerend of passage 38 by the milled slot 44 which is closed by a cover 46braised in place as is cover 42. There is thus provided a continuouspassage through the inner part of bus bar 14 which terminates at endfittings 48 and 50. Bus bar 18 has a corresponding opening 50' (see FIG.3) and bus bar 20 has a corresponding opening 50". Thus cooling fluidsuch as water supplied to the passages maintains the temperatures of thebus bars at a rated value.

Movable bus bars 30 and 32 have similar cooling fluid passages. Morespecifically, bus bar 32, see FIG. 2, has a horizontally extendingpassage 52 and avertically extending passage 54 which communicate withone another at their inner ends and are provided with fittings 56 and 58at the outer edges of bus bar 32. The opposite end of bus bar 32 hasahorizontal passage 60 corresponding to passage 52, a vertical passage 62corresponding to passage 54, which passages intersect interiorly of busbar 32. Passage 60 has an external fitting 64 and passage 62 has anexternal fitting 66 for effecting connection of water supplied to thepassage. Bus bar 30 has cooling passages similar to those described inconnection with bus bar 32.

The cooling passages of bus bars 30 and 32 are fed from hoses 68 whichare connected to a water supply system (not shown) which includespumping and cooling apparatus. The specific details of such apparatusform no part of the present invention and therefore require no detailedexplanation.

Conduits for cooling fluid to fixed bus bars 14, 16, 18 and 20 feedthrough the rear of such bus bars and therefore do not appear in FIG. 1.Suffice it to say there are conduits or hoses corresponding to hoses 68connected to inlet fittings exemplified at 48 and S with respect tofixed bus bar 14.

Because movable switch frame 24 is relatively massive, alinementproblems between movable bus bars 30 and 32 and fixed bus bars 14, 16,18 and 20 would be likely to occur but for the features of the presentinvention. Movable bus bars 30 and 32 are supported for movementrelative to rigid plate 28. For so supporting the movable bus bars thereare installed adjacent the .comers of the movable bus bars in agenerally rectangular pattern four stub shafts 70. Because theinstallation of the stub shafts is identical, only one will be describedin detail in reference to FIGS. 3 and 4. Referring to FIG. 4, stub shaft70 is seen embodied in a bolt having a threaded shaft 72 which isthreaded into an appropriate opening in bus bar 32. Plate 28 isapertured to receive an insulative bushing 74 which is centrally boredto receive shaft 72 and has an outer circular flange 76 for inhibitingthe bushing against inward movement. Bushing 74 is slidable within theopening in plate 28 and has on the interior extension thereofintermediate plate 28 and the movable bus bar a compression springmember, exemplified by a Belleville spring washer 78 which is installedbetween two flat washers '80. Thus it will be seen from FIG. 4 that theforce of spring 78 urges movable bus bar 32 toward fixed bus bar 20;because spring 78 is resilient however a certain degree of upwardmovement of the movable bus bar 32 is afforded. The movable switch frameis so arranged that when force is applied to plate 28 and bus bars 30and 32 by dish-shaped spring 26, compression springs 78 are at leastpartially compressed so that adequate pressure is exerted by the movablebus bars ontofixed bus bars 14, 16, 18 and 20.

For further improving the contact between the movable bus bars and thefixed bus bars, each fixed bus bar is provided with a cylindricconductive member 82 (see FIG. 3) which is preferably formed of copperand braised in a complementary depression in the fixed bus bars.Cylindric member 82 extends outward of the surface of the fixed bus barsand has an arcuate convex surface 84 adapted to contact the innersurface of movable bus bars 30 and 32. In one switch designed accordingto the present invention cylindric members 82 have a diameter of about 2/2 inches, a thickness of about 13/16 inch and a radius of curvature onsurface 84 of about 7 inches.

It will be noted in FIG. 2 that cylindric contact members 82 lie withinthe rectangular pattern defined by stub shafts when the movable bus barsare inbridging relation to the fixed bus bars. This affords optimummovement of the movable bus bars to bring the bus bars into conformityand contact with cylindric contact members 82 notwithstanding a degreeof misalinement of movable switch frame 24- with respect to base 12.

It will also be noted in FIG. 2 that the passages for cooling fluid arearranged to be adjacent to and at least partially surround the point ofcontact between cylindric contact members 82 and movable bus bars 30 and32. More specifically the cylindric contact member mounted in fixed busbar 14 is intermediate fluid passages 36, 44 and 38 which surround thecylindric member on three sides. The cooling passages in movable busbars 30 and 32 are arranged to surround the point of contact withcylindric member 82 on two adjacent sides. The proximity of the coolingpassages to the point of contact between the cylindric contact members82 and the movable bus bars assures that the switch will operate atrated temperatures for virtually all magnitudes of current flowtherethrough. 1 The switch of the present invention operates as follows:in the normal condition, depicted in FIG. 1, it can be assumed that thepositive side of the DC power supply is connected to fixed bus bar 14and the negative side is connected to fixed bus bar 20. It can befurther assumed that the anode of the plating tank is connected to fixedbus bar 18 and the cathode is connected to fixed bus bar 16. In thiscondition dish-shaped spring 26 urges movable switch frame 24 inward andthe force of the dish-shaped spring plus that in compression springs 78assures uniform contact between movable bus bars 30 and 32 and therespective cylindric contact members 82. When polarity reversal isdesired mechanism associated with shaft 22 and more fully described inthe above cited US. Pat. No. 3,315,057, is operated to release the forcesupplied by dish-shaped spring 26 so that the movable bus bars moveoutward on shaft 22 and out of contact with fixed cylindric contactmembers 82. After the switch frame is manually rotated such mechanismagain applies pressure through dishshaped spring 26 so as to urgemovable bus bars 30 and 32 into contact with fixed cylindric members 82.The resilient mount of the fixed bus bars afforded by stub shafts 70 andsprings 78 permit the movable bus bars to move to a degree sufficient tocompensate for any misalinement of switch frame 24 with the fixed busbars. In addition the supply of cooling fluid through hoses 68 and thepassages in the fixed and movable bus bars assures that rated operatingtemperature is not exceeded.

By employing the present invention a reversing switch in which the fixedand movable bus bars are formed by copper bars having a 1 inch by 12inch crosssectional area can safely carry 12,000 amperes and remainwithin the rated temperature rise. The present invention makes possiblea reversing switch having a capacity of up to 24,000 amperes withoutmaterially increasing the physical size thereof.

Thus it will be seen that the present invention provides a polarityreversing switch that has higher capacity within a given temperaturerange without increasing the overall dimensions of the switch. Moreoverthe capacity of the contacting parts to be at least partially selfalining reduces the importance of strict manufacturing tolerances toachieve proper operation. Finally, the present invention lends itself tomanufacture of polarity reversing switches having current ratings farexceeding that which has heretofore been feasible.

Although one embodiment of the invention has been shown and described,it will be obvious that other adaptations and modifications can be madewithout departing from the true spirit and scope of the invention.

What is claimed is:

1. In a high capacity polarity reversing switch of the type including astationary base member having two pairs of stationary terminals, amovable member having internal terminal engaging conductors and beingoperable in a first position to form a circuit between pairs of saidstationary terminals and in a second position to form a circuit betweendifferent pairs of said stationary terminals, and means axially alinedrelative to said base for selectively engaging and disengaging saidmembers in circuit forming positions, the improvement comprising rigidconductor bars constituting said terminal engaging conductors, means forsupporting said rigid conductor bars for movement relative said movablemember toward and away therefrom and toward and away from saidstationary terminals, means for resiliently biasing said rigid conductorbars away from said movable member and toward said stationary terminals,said stationary terminals formed by cylindric conductive members havingone end mounted to said base member and the other end protrudingtherefrom toward said conductor bars, said protruding end beingarcuately convex so as to make contact with said conductor barsirrespective of misalinement of said movable member relative said basemember, said conductor bar supporting means comprising first and secondstub shafts attached to said conductor bars and extending therefrom,means for guiding said stub shafts for sliding movement in said movablemember, said guiding means being disposed so that said stub shafts lieon opposite sides of said cylindric conductive members when therespective conductive bar is in contact with the convex surface of saidcylindric conductive member, and wherein said resilient biasing meanscomprises first and second compression springs circumscribing respectivesaid shafts intermediate said movable member and said conductor bar,said conductor bars and stationary terminals defining a plurality offluid passages therethrough, and means for supplying a cooling fluid tosaid passages.

2. A switch according to claim l wherein said fluid passages extendadjacent at least three sides of said cylindric conductive member.

3. A high current capacity polarity reversing switch comprising a base,four fixed contacts supported on said base in a generally square planarpattern, a switch frame, means for supporting said switch frame forrotative movement on an axis centrally of said square pattern and normalto the plane thereof, means for moving said switch frame along said axistoward and away from said fixed contacts, first and second conductorbars for spanning said fixed contacts, and means for mounting saidconductor bars on said switch frame in parallelly spaced apart relationso that said conductor bars effect a first circuit configuration betweenpairs of said fixed contacts in a first position of said switch frameand effect a second circuit configuration between different pairs ofsaid fixed contacts in a second position of said switch frame from saidfirst position, said mounting means including means for supporting saidconductor bars for movement toward and away from said switch frame andmeans for resiliently biasing said conductor bars away from said switchframe and toward said fixed contacts, said conductor bar supportingmeans including a stub shaft attached adjacent each comer of saidconductor bar and extending therefrom, said stub shafts being in asubstantially rectangular pattern, and means for guiding said stubshafts for sliding movement in said switch frame, and wherein saidconductor bar biasing means includes a compression spring circumscribingeach said stub shaft intermediate said switch frame and said conductorbar, said fixed contacts protruding from said base and being positionedto reside within the rectangular pattern of said stub shafts so thatsaid conductor bar is urged into uniform contact with said fixedcontacts when said switch frame is moved toward said fixed contactsinsaid first and second positions.

4. A switch according to claim 3 wherein said conductor bars define aplurality of fluid passages therethrough, and means for supplying acooling fluid to said passages.

1. In a high capacity polarity reversing switch of the type including astationary base member having two pairs of stationary terminals, amovable member having internal terminal engaging conductors and beingoperable in a first position to form a circuit between pairs of saidstationary terminals and in a second position to form a circuit betweendifferent pairs of said stationary terminals, and means axially alinedrelative to said base for selectively engaging and disengaging saidmembers in circuit forming positions, the improvement comprising rigidconductor bars constituting said terminal engaging conductors, means forsupporting said rigid conductor bars for movement relative said movablemember toward and away therefrom and toward and away from saidstationary terminals, means for resiliently biasing said rigid conductorbars away from said movable member and toward said stationary terminals,said stationary terminals formed by cylindric conductive members havingone end mounted to said base member and the other end protrudingtherefrom toward said conductor bars, said protruding end beingarcuately convex so as to make contact with said conductor barsirrespective of misalinement of said movable member relative said basemember, said conductor bar supporting means comprising first and secondstub shafts attached to said conductor bars and extending therefrom,means for guiding said stub shafts for sliding movement in said movablemember, said guiding means being disposed so that said stub shafts lieon opposite sides of said cylindric conductive members when therespective conductive bar is in contact with the convex surface of saidcylindric conductive member, and wherein said resilient biasing meanscomprises first and second compression springs circumscribing respectivesaid shafts intermediate said movable member and said conductor bar,said conductor bars and stationary terminals defining a plurality offluid passages therethrough, and means for supplying a cooling fluid tosaid passages.
 2. A switch according to claim 1 wherein said fluidpassages extend adjacent at least three sides of said cylindricconductive member.
 3. A high current capacity polarity reversing switchcomprising a base, four fixed contacts supported on said base in agenerally square planar pattern, a switch frame, means for supportingsaid switch frame for rotative movement on an axis centrally of saidsquare pattern and normal to the plane thereof, means for moving saidswitch frame along said axis toward and away from said fixed contacts,first and second conductor bars for spanning said fixed contacts, andmeans for mounting said conductor bars on said switch frame inparallelly spaced apart relation so that said conductor bars effect afirst circuit configuration between pairs of said fixed contacts in afirst position of said switch frame and effect a second circuitconfiguration between different pairs of said fixed contacts in a secondposition of said switch frame 90* from said first position, saidmounting means including means for supporting said conductor bars formovement toward and away from said switch frame and means forresiliently biasing said conductor bars away from said switch frame andtoward said fixed contacts, said conductor bar supporting meansincluding a stub shaft attached adjacent each corner of said conductorbar and extending therefrom, said stub shafts beIng in a substantiallyrectangular pattern, and means for guiding said stub shafts for slidingmovement in said switch frame, and wherein said conductor bar biasingmeans includes a compression spring circumscribing each said stub shaftintermediate said switch frame and said conductor bar, said fixedcontacts protruding from said base and being positioned to reside withinthe rectangular pattern of said stub shafts so that said conductor baris urged into uniform contact with said fixed contacts when said switchframe is moved toward said fixed contacts in said first and secondpositions.
 4. A switch according to claim 3 wherein said conductor barsdefine a plurality of fluid passages therethrough, and means forsupplying a cooling fluid to said passages.